1. Field of the Invention
The present invention relates generally to system fan management for cooling an electronic system and, more particularly, to automatically managing cooling fan operation based upon the configuration of replaceable electronic modules within zones of such an electronic system.
2. Related Art
Advances in the miniaturization of computer, communication and other electronic equipment have led to the development of so-called “blade” systems, which permit several circuit boards (“blades”) to be installed in a single chassis. The chassis typically includes components, such as power supplies, cooling fans, a blade manager, and other components that are shared by all the blades installed in the chassis. The blades typically plug into a backplane of the chassis, which distributes power and data signals between the blades, blade manager, and other components. This arrangement enables a large number of blades to be housed in a relatively small chassis. Oftentimes, the chassis is dimensioned to be mounted in a rack, such as a server rack with other rack-mounted equipment.
Blades are typically designed to be “hot swappable”, that is, they can be installed into or removed from a chassis without removing power from all components in the chassis. This enables an operator or system manager to replace a failed or failing blade with a replacement blade without adversely affecting real-time operations of other chassis components. In addition, spare blades can be installed in a chassis, without activating them, to serve as “standby” blades.
Blades can perform various functions. Most blades contain entire computers, including single or multiple processors, memory, and network interfaces. Most computer blades are used as servers while others are used as communication devices, such as routers, firewalls or switches. Some blades contain specialized hardware components, in addition to or instead of processors, memory, etc. Typically, any type of blade can be plugged into any slot of a chassis. This enables an operator or system manager to “mix and match” blades in a chassis so that requisite operations can be performed by the blade system. In addition, the mixture of blade types can be changed to accommodate changes in operational requirements.
Some server blades include disk drives. Other blades access disk drives that are located elsewhere in the chassis or are connected to the chassis by computer network hardware. The blade manager establishes logical network connections between these blades and off-blade disk drives. Since these blades can be connected to different disk drives containing different software at different times, these blades can execute different operating systems and/or application programs, and can access different data at different times. For example, a system operator might choose to logically connect a blade to different disk drives to execute different application programs at different times of a day. In another example, if a blade fails, logical connections from off-blade disk drives that were formerly used by the failed blade can be redirected to a replacement or hot standby blade.
Some blades can be field-upgraded, such as by installing additional memory, processors or other components on the blades. In contrast, some manufacturers prefer to produce blades that are fully populated with such additional hardware. These manufacturers selectively enable or disable the additional hardware when the blades are manufactured, to tailor the blade capabilities to the customers' initial needs and budgets. Later, if a customer purchases a license to upgrade a blade, all or a portion of the additional hardware can be enabled without reconfiguring (which requires removal of the blade from the chassis) or replacing the blade.
Though blade servers provide many advantages, several engineering challenges arise when using bladed servers. Among these challenges is the challenge of designing and operating a bladed system such that the heat generated by the blades is sufficiently removed in the limited space available in the chassis that hosts the system. Some known power limiting strategies include powering down a CPU functional unit, e.g., a floating point unit or an on-die cache, or trading off speed for reduced power consumption in a hard drive. To address heat dissipation challenges, bladed server systems can be designed with an underlying power and thermal envelope. For example, when a chassis that hosts a bladed system has a limited amount of airflow available to cool the blades (i.e., when the system can only dissipate a limited amount of heat), then the chassis is designed for a limited amount of power consumption and an associated limited performance of the blades.
As a result of the modularity and flexibility of such bladed systems however, different portions of a chassis that holds the blades may contain more or fewer blades, blades that run hotter than other blades, blades with processors that run at different clock frequencies than processors on other blades, and/or blades that have been turned on or turned off during operation of the bladed system. As a result, the cooling needs within a particular chassis can vary from time to time, and, in particular, the cooling needs of more than one cooling region within the blade chassis (each cooling region served by one or more separate cooling fans) can vary from time to time. In order to optimize the usage of available power in a bladed system, previous systems have changed the speed of all of the fans in a chassis together, without regard to the location of individual fans in the chassis, based on system parameters such as temperature within the chassis.